Simplify the following expression: $r = \dfrac{5}{3n} \div \dfrac{7}{8n}$
Dividing by an expression is the same as multiplying by its inverse. $r = \dfrac{5}{3n} \times \dfrac{8n}{7}$ When multiplying fractions, we multiply the numerators and the denominators. $r = \dfrac{ 5 \times 8n } { 3n \times 7}$ $r = \dfrac{40n}{21n}$ Simplify: $r = \dfrac{40}{21}$